10-10-2014, 02:19 PM
The dynamic properties such as logarithmic decrement and dynamic modulus of
concrete are important parameters required in the design of concrete structures
to withstand dynamic loadings. In service, due to the stresses acting, concrete
could have suffered some internal micro-cracking. Hence it is essential to know
the influence of such cracking on the logarithmic decrement etc. on concrete.
In the present investigation a total of 66 specimens cast out of three concrete mix,
two mortar mix and cement paste were tested. Logarithmic decrement and
dynamic modulus are obtained after subjecting the specimens to a prior-stress of
different percentages of ultimate stress. These are determined by making ‘sonic
resonance test.’ In the investigation, the logarithmic decrement is found to
increase with respect to an increase of prior-stress, while in some cases it is found
to decrease when the prior-stress is increased. The dynamic modulus is found to
be higher by about 10% to 25% compared to static modulus